The present invention relates generally to the fabrication of plastic electrical outlet boxes and, more particularly, to a method and apparatus for forming the closure members of cable entry ports in such boxes to permit relatively easy entry of an electrical cable into the box through the ports.
Outlet boxes are widely used in the construction industry for connecting electrical cables in the walls of a building to the desired wiring devices--i.e., receptacles and switches--by which access is provided to electrical power. While outlet boxes have been fabricated from metals, such as steel or aluminum, for physical strength, boxes fabricated from a moldable thermo-plastic material have been receiving increasing commercial acceptance. The plastic boxes are advantageous in their ease of manufacture (being moldable in a simple two-part injection mold) as well as their light weight.
Virtually all boxes, including the plastic boxes, have cable entry ports formed in the box walls to admit an electrical cable into the box. Various structures have been designed for keeping the ports closed prior to use, yet permitting admission of an electrical cable when desired. One recent design, incorporated in boxes sold by Slater Electric Inc. of Glen Cove, N.Y. (the assignee of the present application), includes panel members at the rim of the cable entry port, joined together by a webbing or like structure to close the port. This port closure means is adapted to withstand prescribed forces under various conditions yet permits opening when desired by forcing the end of the cable against the web.
Although the webs can be molded to a precise thickness to satisfy industry standards, some difficulty may be experienced in the flow of material in the area of the cable-entry ports during the molding operation. Too little material, of course, raises the danger of failing the industry strength tests. However, by increasing the thickness of the webbing, the ports may not be easily opened by forcing the cable end against the web.
Accordingly, it is an object of the present invention to provide new and improved method and apparatus for forming cable entry port closure means in molded plastic electrical outlet boxes, which provides closure of each cable entry port sufficient to withstand all industry tests, yet capable of being opened by forcing the end of a cable against the closure means.